Various means have been used in the prior art to increase the density of the propellant charge beyond 0.8 gm/cc for large caliber weapons such as howitzer and cannon. The prior art propellant charges usually comprise randomly assembled multi-perforated, small length-to-diameter ratio grains. It is generally desirable to increase the bulk density of the propellant charge in order to achieve greater performance from the weapon. Since the propellant chamber frequently has a fixed volume, it is advantageous to use a high bulk density charge to obtain greater amounts of energy for the available space. Some prior art devices try to solve this problem by vibrating chopped, multiperforated, right-circular cylindrical propellant grains. It has been found that vibration reduces the amount of free volume (ullage) within the charge chamber, but not as efficiently as desirable because these grains after vibration, are still randomly oriented and have air spaces therebetween. Other prior art devices are bundled, right-circular grains diametral surfaces. Some prior art devices try solving the increased density problem by consolidating the charge by compacting and crushing the grains sometimes in the presence of a propellant solvent. The problem with the aforementioned consolidation process is that it produces a circular wafer having limited thickness or height.
The aforedescribed prior art devices, while each contributing somewhat to an increase in the bulk charge density, have never fully eliminated the ullage problem and consequently have not, in most instances, efficiently exploited the full available volume of a propellant chamber. Additional problems are frequently encountered when vibration and consolidation techniques are used. There is an element of risk always associated with these packing procedures. Because of accidental initiation it is never completely safe to vibrate or compress energetic materials such as must be used in propellant charges. One of the problems with the use of propellant grains made by the consolidation technique is that the ignition and burning of the charge is highly dependent upon the way that the compacted material breaks up under the shock of ignition.